Paper-based Insulator Electrokinetics for Microscale Particle Manipulation and Analysis

Abstract

Insulator-based electrokinetics (iEK) integrates insulating structures within microchannels to induce local curvature in electric field lines, resulting in regions of high field intensity. This technique has been employed in various applications, such as DNA enrichment, liquid biopsy, biomarker screening, and protein folding analysis, among others. In this paper, we present a new electrokinetic particle manipulation technique using insulating paper fibers to generate high electric field gradients. The technique involves confining nonwoven fiberglass paper channels and copper tape electrodes within thin PDMS sheets fabricated using a low-cost paper-PDMS technique called “Microfluidic pressure in paper” (μPiP). We apply an AC electric field perpendicular to the flow direction to dielectrophoretically trap and separate different polystyrene particles within the paper channels. We further present a 2D computational model of the paper structure and introduce the concept of a 3D “paper unit cell” to analyze the formation of regions with high electric field gradients within the paper structure. This model will be useful for researchers studying paper-based electrochemical sensors, paper-based free-flow electrophoresis and isotachophoresis devices, and lateral flow assays. This new platform enables the development of robust, low-cost, and portable next generation microscale electrokinetic systems for a wide variety of sample purification, quantification and liquid handling applications.